Recommended powersupply for LM3886?

[crosstalk]

Hello,

Have anyone here used the DIYCART LM3886 Overture Kit? Is there a recommended power supply for it? Or a circuit diagram?

I am looking for around 35W on a 8 ohm load.

Also what precautions should be taken for the grounding? (Power ground/Signal ground)

This is my first 3886 build, thus the questions.

Thanks in advance.

 

[shaan]

Hello,

Have anyone here used the DIYCART LM3886 Overture Kit? Is there a recommended power supply for it? Or a circuit diagram?

A basic dual PSU with total 40,000uF will be good enough for two channels. This is a suitable supply from the same vendor but the fuses are on the wrong side (!!!).
https://diyaudiocart.com/kits/power...APPS08-35A-63V-40000uF-Dual-Rail-Power-Supply

I am looking for around 35W on a 8 ohm load.

Use a 22V-0-22V/5A transformer.

Also what precautions should be taken for the grounding? (Power ground/Signal ground)

This is my first 3886 build, thus the questions.

Thanks in advance.

If the boards have a single ground connection then all's well. Make sure the input cable's shield doesn't short to chassis metal.

Take a wire from PSU's ground and fasten its other end to the chassis with a loop breaker in series. Short the chassis directly to mains Earth ground. If the amplifier board doesn't have a speaker return terminal then route the speaker return directly to PSU ground.

 

[avesbilal]

A basic dual PSU with total 40,000uF will be good enough for two channels. This is a suitable supply from the same vendor but the fuses are on the wrong side (!!!).

Hi Shaan,

You mean the fuses should be after capacitor bank?

I too have put fuses before bridge rectifier in my PeeCeeBee V3 built. [emoji33] (I just copied one of the schematic from internet)


Regards
Bilal

 

[shaan]

Yes the fuses should be installed between PSU cap bank and amplifier. Otherwise they'll fail when their protection is needed most.

 

[jls001]

Eightaudio also has PSU suitable for 3886. Please check out their website.

Of course you'll need to buy dual rail transformer from other vendors like Torotrans Pune or Electroharmonic Hyderabad.

 

[avesbilal]

Crosstalk: If you want to save money you can build your own Power supply on a plain PCB board, you need to do point to point connection, it would cost you half then buying online. I built my own Power supply. If you want circuit diagram there are plenty available online or I can provide you one. Just make sure you put the fuses at the right place as mentioned by Shaan.

Shaan: thanks for pointing out that error.

Regards
Bilal

 

[crosstalk]

A basic dual PSU with total 40,000uF will be good enough for two channels. This is a suitable supply from the same vendor but the fuses are on the wrong side (!!!).
https://diyaudiocart.com/kits/power...APPS08-35A-63V-40000uF-Dual-Rail-Power-Supply



Use a 22V-0-22V/5A transformer.



If the boards have a single ground connection then all's well. Make sure the input cable's shield doesn't short to chassis metal.

Take a wire from PSU's ground and fasten its other end to the chassis with a loop breaker in series. Short the chassis directly to mains Earth ground. If the amplifier board doesn't have a speaker return terminal then route the speaker return directly to PSU ground.

Thanks Shaan! Much appreciated.

The boards are yet to arrive.

For the ground loop breaker, do you recommend a circuit?

 

[crosstalk]

Yes the fuses should be installed between PSU cap bank and amplifier. Otherwise they'll fail when their protection is needed most.

True that. This means, that PSU is not any good and better to have one built?

 

[crosstalk]

Eightaudio also has PSU suitable for 3886. Please check out their website.

Of course you'll need to buy dual rail transformer from other vendors like Torotrans Pune or Electroharmonic Hyderabad.

I have got torroidal transformers from Torotrans (Mr. Mahesh) previously, but R-core or Torroid which is better? Googled and did not get any significant hints that one is better than the other. :lol:

 

[crosstalk]

Crosstalk: If you want to save money you can build your own Power supply on a plain PCB board, you need to do point to point connection, it would cost you half then buying online. I built my own Power supply. If you want circuit diagram there are plenty available online or I can provide you one. Just make sure you put the fuses at the right place as mentioned by Shaan.

Shaan: thanks for pointing out that error.

Regards
Bilal

Hi Bilal,

I can build it on a plain PCB board.

Will this work?

 

[HormusPeston]

Hi Crosstalk,
The power supply looks fine. Do you really need a set of ultra-fast diodes for a 50Hz supply? Opinions are divided on this matter with strong arguments on each side -- e.g., the additional snubbers required are justified by a "cleaner sound" and so forth . In my case, I prefer a simple bridge made with 1Ns or a composite ready-made bridge which you can fasten to the case. Fewer components are better, etc.
Cheers,
~HP

 

[HormusPeston]

Hi again,
I seem to remember powering one of these many years ago on 12V rails from a salvaged computer SMPS . You have to waste power by loading the 5V rail but it sounded OK!
Cheers,
~HP

 

[crosstalk]

Hi Crosstalk,
The power supply looks fine. Do you really need a set of ultra-fast diodes for a 50Hz supply? Opinions are divided on this matter with strong arguments on each side -- e.g., the additional snubbers required are justified by a "cleaner sound" and so forth . In my case, I prefer a simple bridge made with 1Ns or a composite ready-made bridge which you can fasten to the case. Fewer components are better, etc.
Cheers,
~HP

Honestly I am not a very learned person on electronics. It is just my hobby. I know a few basic stuff, can read schematics and can solder really really well :lol:

 

[shaan]

Will this work?

Yes it will and is a very good supply for Class-A application. However, 3886 is an amazingly good IC regarding PSRR so you may want to do the following mods:

a. Replace all MUR860 with 10A10. Or just use two KBPC3510.
b. Remove C1, C2, C9 and C10.
c. Remove R5 and R6.
c. Replace R3 and R4 resistors with thick wire link.

All the best.

 

[avesbilal]

Yes it will and is a very good supply for Class-A application. However, 3886 is an amazingly good IC regarding PSRR so you may want to do the following mods:

a. Replace all MUR860 with 10A10. Or just use two KBPC3510.
b. Remove C1, C2, C9 and C10.
c. Remove R5 and R6.
c. Replace R3 and R4 resistors with thick wire link.

All the best.

Hi Shaan,

Don't you recommend to have 0.1uf film capacitors for bypass at each rails?

I also think it is good idea to add one LED per rails with appropriate resister.

Edit: sorry didn't see there are already bypass c7 and c8 caps in the circuit.


Regards
Bilal

 

[crosstalk]

Yes it will and is a very good supply for Class-A application. However, 3886 is an amazingly good IC regarding PSRR so you may want to do the following mods:

a. Replace all MUR860 with 10A10. Or just use two KBPC3510.
b. Remove C1, C2, C9 and C10.
c. Remove R5 and R6.
c. Replace R3 and R4 resistors with thick wire link.

All the best.

Thanks Shaan!

Will keep posted.

 

[tcpip]

Shaan, what is your view on the single bridge vs two bridges issue? Do two bridges really make any audible or measurable difference? (In my view, two bridges will make a very small negative difference.)

 

[crosstalk]

Shaan,

Do you think this PCB x 2 will be a good one for the PSU

Class A Amplifier Rectifier Filter Power Supply Board PSU Bare PCB | eBay

It is for KBPC3510.

 

[tcpip]

Interesting PCB. It has support for both form factors of bridge rectifiers.

 

[HormusPeston]

Shaan, what is your view on the single bridge vs two bridges issue? Do two bridges really make any audible or measurable difference? (In my view, two bridges will make a very small negative difference.)

Hi tcpip,

Interesting point. Never thought about it. Is the negative difference you mentioned because of the drop in voltage due to the additional diodes?

The only benefit I can think of is that the currents on the positive and negative side would have different return paths to the transformer... Not sure if that makes any difference in terms of audio quality.

Cheers,
~HP